1. Technical Field of the Invention
The invention relates to a method and devices for the provision of services in visited telecommunication networks.
2. Description of Related Art
Many subscribers of mobile telecommunication networks, such as a GSM (Global System for Mobile Communication) or a UMTS (Universal Mobile Telecommunication System) network, use services offered by network operators or others. Examples for such services are information services, stock exchange information services, schedule information or emergency call services such as police emergency calls or life saving services. A service as defined in the present application can also be an organisation or private person working or known on an international basis, or a service offered in a comparable manner in a multitude of networks. In many cases it is desirable to call a service without knowing the number of said service or without having to find it out. Such a situation can arise, for example, if a subscriber wants to check different alternative transport possibilities at the end of an event. In this case it is less desirable, if he has to inquire and remember a multitude of phone numbers by means of an information service first. In an emergency case frequently the situation arises, where a person involved no longer remembers the correct emergency call number. Here, too, it does not appear sensible, if he has to find out the corresponding phone number first.
As far as emergency call services are concerned, a large number of simplifications are offered enabling a subscriber to reach an emergency call service without knowing the phone number. Patent FI-9500335 introduces an emergency call device, which dials a desired emergency call service by operating one single key. The utility model DE-29809959 describes a similar device, wherein a subscriber can choose from a plurality of emergency call services. Both devices have pre-set emergency call numbers memorised internally, thereby requiring that a subscriber is presently located in the applicable area of the pre-set numbers. Thus, said devices can only be used in one or a few telecommunication networks.
The U.S. Pat. No. 5,719,929 describes a system wherein character strings used for dialling services, in said patent named special numbers, are stored in a mobile user equipment. A phone number, entered by a mobile subscriber, is compared in the mobile user equipment with a set of stored special numbers. If the dialled number is found among the stored special numbers, a special number indicator is sent to a mobile network. The mobile network translates the special number indicator to a phone number for the service indicated by the indicator.
By this, a mobile subscriber can use the same phone number world wide to reach a service.
However, the system introduced by the U.S. Pat. No. 5,719,929 would not recognise a special number that is used in a visited mobile telecommunication system for dialling services.